The present invention relates to a connector having contacts connected to a board such as a printed circuit board, and a method of producing such a connector and, in particular, relates to a connector having contacts connected by soldering to conductive portions connected to a circuit of a board, and a method of producing such a connector.
In conventional connectors, there is available such a type of connector that is used so as to be mounted on a board for mutual connection between electronic or electric devices.
The connector comprises an insulator, and a plurality of contacts retained by the insulator. A terminal portion of each contact is bent from a substantially horizontal direction relative to the board to a substantially perpendicular direction so as to extend to the exterior of the insulator. A tip portion of the terminal portion serves as a solder joint portion that is inserted into a corresponding one of through holes formed in the board. The solder joint portion is fixedly soldered to the board in the state where it is inserted in the through hole. The solder joint portion is for obtaining electrical continuity with a corresponding one of conductive portions connected to an electronic circuit formed on the board (e.g. see JP-A-H04-61767).
When the connector is mounted on the board, inasmuch as environment of using the electronic circuit is often in an engine room of an automobile, or at a portion that is subjected to influence by variation in temperature of the open air, the board, the insulator, and the contacts inevitably repeat thermal expansion and retraction due to temperature variation in that atmosphere.
Consequently, a load is applied to the solder joint portion, and there is possibility of occurrence of a crack in a soldering portion. If the crack is generated in the soldering portion like this, the electrical continuity becomes incomplete at the cracked portion so that there is possibility of occurrence of failure such as electrical chattering.
The solder joint portion is fixedly soldered to the board in the state where the solder joint portion passes through the board and is exposed to a side of the board opposite to a side thereof where the connector is mounted. Accordingly, if the terminal portion having a length dimension shorter than a prescribed length dimension is soldered to the conductive portion of the board, there is possibility of occurrence of failure wherein the formation of the solder joint portion becomes incomplete, and therefore, the electrical continuity becomes incomplete at the solder joint portion.
On the other hand, if the terminal portion having a length dimension greater than the prescribed length dimension is soldered, there is possibility of occurrence of failure wherein the solder joint portion of the terminal portion interferes with another board, device or the like to thereby cause mechanical damage thereto or electrical leakage from the contact.
As other conventional connectors relating to the present invention, there are disclosed ones wherein a stress absorbing portion of a circular arc shape is formed at a bent portion of a terminal portion of each contact (e.g. see JP-A-H09-69371, JP-A-H07-153508, and JP-A-H06-203896).
With respect to the terminal portion of the contact formed with the stress absorbing portion, processing using at least three bending jigs is required for forming the stress absorbing portion of the circular arc shape.
Further, with respect to a matrix array connector having upper and lower rows of contacts that are arranged in a straight line vertically, there has been a problem that it is not applicable because, upon processing a terminal portion of a contact in the lower row, one of the jigs interferes with a contact in the upper row right over it.